Power-supply system for radiotransmitters



April 7, 1931. L. A. GEBHARD POWER SUPPLY SYSTEM FOR RADIOTRANSMITTERS Filed Aug. 19. 1927 X w w INVENTOR. ajzard 2? TORNEY jazzzsfl. 62

Patented Apr. 7, 1931 UNITED STATES PATENT OFFICE LOUIS A. G EBHARD, OF WASHINGTON, DESTRECT C1" COLUMBIA, ASSIGNOB, BY MESNE ASSIGNMENTS, TO FEDERAL TELEGRAPH COMPANY, A CORPORATION 013 CAL?- FORNIA POXVER-SUPPLY SYSTEM FOR- RADIOTRANSMITTERS Application filer. August 19, 1827. Serial No. 214,197.

My invention relates broadly to rectifier systems and more particularly to a system of regulation for vacuum tube rectifier systems.

One of the objects of my invention is to provide a rectifier system for the power supply circuits of high frequency signal trans mission systems wherein means are provided for compensating for the rapidly varying conditions of load.

Another object of my invention. is to provide a simplified circuit arrangement for a high power rectifier system in signal transmitter circuits having special regulation circuits for varying degrees of load.

Other and further objects of my invention will be understood from the following specification by reference to the accompanying drawing which shows the vacuum tube rectifier circuit of my invention applied to a signal transmission system.

A vacuum tube rectifier has inherently poor regulation due to the large voltage drop in the tubes and associated circuits, when the load current is near the full capacity of the tubes. For economical operation the load current must be kept near this value other wise the tube capacity would be excessive.

Where a number of radio transmitters are operated from a common direct current source, good regulation is imperative to pre vent intermodulation between sets, reduction of power output when more than one set is operated, and excessive no load potentials which tend to cause tube trouble as well as require a larger safety factor in design than would otherwise be necessary.

One of the most serious difiiculties to be encountered in holding the direct current terminal voltage constant with a load consisting of a number of radio transmitters, is that the load is on and off very rapidly, making such devices as are normally used for controlling voltage entirely out of the question. In order to function properly the apparatus must be capable of functioning at the rate governed by the sending speed. The method about to be described has the desirable qualities outlined above necessary to give good voltage regulation.

, Referring to the drawing reference character 4 represents the rectifier plate supply transformer, the primary 5 of which is energized from alternating current source 13 through secondary 1 of booster transformer 3.

Form the secondary 6 of transformer 4 to the direct current output terminals 12, the circuit includes the rectifier and filter sys tem. The secondary 6 of transformer 4 is divided into two sections to provide full wave rectification. although this is not entirely essential for the operation of the circuit of my invention since half-wave rectification could be used as well. The center tap on second my 6 is connected to one of the direct current output terminals 12. The outer ends of the secondary 6 connect to anodes of rectifier tubes 7. The filaments of tubes 7 are supplied from alternating current source 17 through transformer 15. The voltage on the filaments is controlled by rheostat 16. The condensers 8 and reactors 9, act as a filter to smooth out the voltage irregularities. The direct current output to the radio transmitter is taken from terminals 12. I

The primary 2 of booster transformer 3 is connectedin series with number of reactors 10, to alternating current source 13. The source supplying primary 5 of transformer 4, and that supplying primary 2 of transformer 3, may be independent but must be of the same frequency and approximately in phase. The number of reactors 1O depends upon the number of radio transmitters which are to operate from the common rectifier source. he method described may be used with a single transmitter, or with a number of transmitters. The diagram shows provision for four transmitters, only one of which is illustrated. This consists of a piezoelectric controlled oscillator 23, supplying energy to control amplifier tube 24, which in turn supplies energy to the antenna circuit 25. The keying system of this transmitter consists of a number of resistors 26, with direct current source 27, connected to grid of tube 24 through coil 28. Any type of transmitter or keying system may be used with the method described.

The reactors 10, are short-circuited individually by contacts of relays 11. The coils 26 of relays 11 are connected through contacts 27 of relays 18 to source 14;. The coils of relays 18 are connected either in series as shown in the drawing, or in parallel with coils of relays 19, and then through control keys 21 to source 22. The contacts of relays 19 con nect through line 20 to the keying systems of the radio transmitters; in the transmitter shown in the drawing the connection includes resistors 26 and source 27 controlling the grid of amplifier tube 2-1. Relays 18 are generally large in order to handle the power required, but it the power necessary is small, contacts of relays 18 may directly short-circuit the reactors 10 instead of operating indirectly by controlling coil circuits of relays 11.

In normal operation, the operator controls key 21, which when depressed energizes coils of relays 19 and 18. Contacts of relay 19 control the grid circuit of tube 2d of the radio transmitter causing power to be drawn from the rectifier and also causing a radio signal to be emitted from antenna andcounterpoise system 25. Simultaneously with this, the contacts of relay 18 close the coil circuit of relay 11 to a source 1% and thus in turn cause the closing of contacts of the relay 11, short-circuitin g reactor 10. This causes an increase in voltage impress-ed on primary 2 of the transformer 3, causing an increase in voltage of secondary 1, and therefore an increase in voltage impressed on primary 5 of transformer a. This causes increase in voltage of secondary 6, resulting in an increase in direct current voltage and compensating for the drop caused by the load taken by the radio transmitter. lVhen the key 21 is released the load is removed from the rectifier and simultaneously the short-circuit is removed from re actor 10 and thus the terminal voltage of the rectifier is held nearly constant.

If two keys are depressed at one time, two reactors are shortcircuited, resulting in a still higher voltage impressed on transformer 3 and therefore transformer l, causing proper compensation of voltage drop due to increased load and thus the terminal voltage is held constant. hen any number of transmitters are keyed simultaneously or inde pendently they individually compensate for the drop caused by the loads they take.

The compensation with the use of reactors 10 is accomplished partially by a voltage change at the secondary 1 of transformer 3, and partially by a change in phase as referred to source 13. Reactors 10 may be replaced by resistances.

The reactance of reactors 10 may be adjusted by taps or otherwise so that the compensation is correct for the particular load of the transmitter it is connected to through relays. When resistances are used in place of reactors, they are also made adjustable,

The only'power the booster transformer 3 must supply is that necessary to make up for the voltage drop, due tothe loads plus certain losses which are comparatively small. Therefore, relays 11 need not be excessively large andmay have high operating speeds. As pointed out before, if the power is low enough relays 11 may be eliminated and relays 18 may operate directly.

The improvement of my invention may be applied to rectifiers operating from sources of more than one phase, in which case additional relays and reactors (or resistances), must be provided. The coils of relays of corresponding reactors may be connected in series or parallel and controlled from the single key relays as shown in the drawing.

The device herein outlined may be applied to other loads than that of a radio transmitted and may be used under conditions where pres ent available devices are not sufficiently rapid in action.

While I have described my invention in one of its preferred embodiments, I desire that it be understood that modifications may be made and that no limitations upon my invention are intended other than are imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent oi the United States is as follows: 7

1. In a signal transmission system, a high frequency oscillator and power amplifier circuit, means for energizing said power amplifier circuit, a keying circuit for controlling the transmission of signals from said power amplifier by varying the grid electrode potential of said power amplifier, and means connected between said keying circuit and said first mentioned means for regulating the energization of said circuits in accordance with the transmission of signals, said second mentioned means comprising an impedance system and relays, said relays being controlled by said keying circuit to regulate the value of said impedance system to keep the energizing voltage of said power amplifier circuit substantially constant.

2. In a signaling system, a high frequency power amplifier circuit,,means for supplying energy to said circuit, a keying circuit and means comprising a plurality of relays and impedances controlled by said keying circuit for compensating for the loading eflect of said first mentioned circuit by correspond ing changes in the power impressed upon said first mentioned circuit in accordance with the transmission of signals.

3. In a signaling system, a high frequency oscillator and power amplifier circuit, a power source of alternating current, a rectifier connected with said source for impressing rectified current upon the circuits of said power amplifier, a'keying circuit, and means connected between said power source, said rectifier and said keying circuit for compensating for the efi'ects of variable loading with respect to said power source in accordance with the transmission of signals, said means comprising a plurality of relays and impedances, said relays being adapted to short circuit said impedances when said keying circuit is energized.

4. In a signaling system, a high frequency oscillator and power amplifier, a power source of alternating current, a rectifier interposed between said power source and the circuits of said power amplifier, a keying circuit and a booster coil connected between said rectifier and said power source and controlled by said keying circuit for compensating for the effects of variable load offered by said power amplifier in accordance with the transmission of signals.

5. In an electric system utilizing direct current rectified from a source of alternating current power, the combination of a source of alternating current power, one or more rectifiers for converting said alternating current power into direct current power, a load upon the direct current side of said rectifiers, a means for varying the direct current load, means operable with said first means for regulating the voltage of the rectifier by controlling the magnitude and phase of the alternating current voltage supplied said rectifier, said second means comprising a transformer the secondary of which is in circuit with the alternating current supply to the rectifier, a plurality of impedances connected into circuit with the primary of said transformer, a plurality of relays for short circuiting said impedances and means for operating said relays simultaneously with the variation in load.

6. A signal transmission system comprising an oscillator and power amplifier circuit, a keying circuit for modulating the output of said power amplifier, a power source of alternating current, a rectifier for supplying rectified current from said power source to the circuits of said power amplifier circuit, an inductance device comprisng a pair of windings, one of said windings being interposed in series between said power source and saidrectifier, and the other of said windings being controlled by said keying circuit for compensating for the effects of variable loading in accordance with the transmission of signals.

7. In an anode supply for electron tubes the combination of a high voltage transformer adapted for energizing the anodes of electron tubes, and means for keeping the voltage across the primary winding of said transformer substantially constant under full load and no load conditions, said means comprising a plurality of impedance units, abooster transformer and relays, said impedance units being connected in series with the primary winding of the booster transformer into circuit with the primary source of supply of said high voltage transformers said relays being connected to short circuit direct current rectified from a source of al-' ternating current power, a source of alternating current power, a plurality of direct current loads, a plurality of contro keys each connected so as to respectively control the operation of each of said'loads, a booster transformer having two terminals and an intermediate connection, a plurality of reactance elements equal in number to the number of control keys, a rectifier unit, the intermediate connection of said booster transformer being connected to the first terminal of said source of alternating current power, said reactance elements being connected in series between the second terminal of said source of alternating current power and one terminal of said booster transformer, the input of said rectifier unit being connected to said other terminal of said booster transformer and said second terminal of said source of alternating;

voltage regulation of direct current power delivered at common load terminals to aplurality of loads, a source of alternating current power, a rectifier unit supplied with alternating current and delivering direct current power to said load terminals, a booster transformer having two terminals and an in termediate connection, a plurality of reactance elements equal in number to the number of loads connected in series between the first terminal of said source of alternating current power and one terminal of said booster transformer, a short-circuiting switch connected across each said reactance element, said intermediate connection of said booster transform er connected to the second terminal of said source of alternating current, the input of said rectifier unit connected to said first terminal of said source of alternating current power and to said other terminal of said booster transformer, a plurality of control keys equal in number to the number of loads, each of said keys being so connected as to control one of said loads, and means wherey by the switch across a given reactance element is closed when the control key correspon ding to said reactance element is actuated to operate its corresponding direct current load, whereby the voltage delivered to said common load terminals is regulated.

10. In a radio transmission system, a plu- 4 wee-224 rality of generator units for generating high frequency currents each of said units adapted to use direct current power, a control key for each of said generator units, a source of alternating current power, a rectifier unit supsaid source of alternating current power, the

input of said rectifier unit connected to the other terminal of said booster transformer and to the first terminal of said source of alternating current power, and individual means connected between each control key and its corresponding reactance short-circuitings-witeh whereby said corresponding reactance is short-circuited when a given control'key is actuated to operate its corresponding generator unit, wherebythe direct current voltage delivered to said generator units is regulated and uniformity of operation of said generator units is maintained when said control keys are actuated at high speeds.

' LOUIS A, GEBHARD. 

